Neutralizing antibodies against influenza A in pigs before and after the 2009 pandemic, Luxembourg.

Neutralizing antibodies against different swine influenza A viruses and pandemic H1N1 were analyzed in pigs before and after the pandemic. While in 2009 neutralization of the pandemic virus could be explained by cross-reaction with swine influenza viruses this was not the case in at least 2 farms in 2012.